all the displays in stores only shows the black touch cover. it looks a bit thicker than the colored ones but then again I haven't held any of the colored ones yet.
That touch cover is probably one of the original ones that shipped as a bundle with the 32gb model. Yes it is thicker, it also has a felt like bottom. I don't know, but I assume if you buy an individual touch cover that it would be the updated "thinner" model, though I can barely tell the difference and use both my original black, and a red one I bought a few months in.